[TriLUG] Postfix Woes

[Aaron S. Joyner]

Aaron Bockover wrote:

>Oooh! This may not be a total Postfix issue after all. The name servers
>for my domain (rmmp.org) are at ZoneEdit. I have an MX record set to
>mail.rmmp.org. 
>
>When I telnet to rmmp.org (25 or 26, depending on what network I'm
>behind), I can talk with the SMTP server. However, when I try to get to
>mail.rmmp.org, I get a host not found. I'm hoping this is where the
>problem is. Seems quite likely.
>
>In ZoneEdit, under my MX config for the domain, I have:
>
>mail.rmmp.org "handles mail" 1st "for domain" rmmp.org
>
>For the IP (A) records, I have rmmp.org and www.rmmp.org pointing to the
>IP address of the server. Do I also need a mail.rmmp.org A record mapped
>to an IP address? My initial thoughts that were since mail.rmmp.org
>"handles mail" for rmmp.org, and rmmp.org has an A record, I wouldn't
>need one explicitly for mail.rmmp.org. I'm going to give this a shot,
>but still don't know if it's correct.
>  
>
Your thinking is correct.  You need an A record for mail.rmmp.org in 
order for your setup to work.  The MX record simply defines which A 
record handles mail for which domain.  I.e. if I send mail to 
foo at rmmp.org, it looks at the MX record for rmmp.org to find out which A 
record to contact with the message.  If no MX record exists, it looks 
for an A record for rmmp.org.  So alternately, you could remove the MX 
record, but using an MX is generally the preferred way of handling 
things, as it's more explicit.  The additional functionality that MX 
records allow (load balancing, priority-based fail overs, mail handling 
separate from the machine actually listed as the root of the domain, 
etc) probably isn't necessary in your setup, but it's good to understand 
and get comfortable with.  :)

Aaron S. Joyner